Exclude multinode tests from octavia stable/newton
Exclude multinode tests from octavia stable/newton

Octavia stable/newton did not have multinode gate support.  We need
to exclude the multinode tests from stable/newton.

Change-Id: I667d67f559d3dd4bb894d5890ea3081146988dd8

openstack-infra/project-config,openstack-infra/project-config